fixed bug 209 (SQL_SELECT_LIMIT and query cache incompatibility)

mysql-test/r/query_cache.result:
  test of SET OPTION SQL_SELECT_LIMIT
mysql-test/t/query_cache.test:
  test of SET OPTION SQL_SELECT_LIMIT
sql/sql_cache.cc:
  layout fixed
  SQL_SELECT_LIMIT stored in query cache now
sql/sql_parse.cc:
  room for SQL_SELECT_LAYOUT storing added

mysql-test/r/query_cache.result

@@ -581,3 +581,21 @@ show status like "Qcache_queries_in_cache";
 Variable_name	Value
 Qcache_queries_in_cache	0
 drop table t1;
+create table t1 (a int);
+insert into t1 values (1),(2);
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	0
+select * from t1;
+a
+1
+2
+SET OPTION SQL_SELECT_LIMIT=1;
+select * from t1;
+a
+1
+show status like "Qcache_queries_in_cache";
+Variable_name	Value
+Qcache_queries_in_cache	2
+SET OPTION SQL_SELECT_LIMIT=DEFAULT;
+drop table t1;

mysql-test/t/query_cache.test

@@ -401,7 +401,6 @@ select * from t1 where id=2;
 #
 # Load data invalidation test
 #
-
 create table t1 (word char(20) not null);
 select * from t1;
 show status like "Qcache_queries_in_cache";
@@ -412,7 +411,6 @@ drop table t1;
 #
 # INTO OUTFILE/DUMPFILE test
 #
-
 drop table if exists t1;
 create table t1 (a int);
 insert into t1 values (1),(2),(3);
@@ -421,3 +419,16 @@ select * from t1 into outfile "query_caceh.out.file";
 select * from t1 limit 1 into dumpfile "query_cache.dump.file";
 show status like "Qcache_queries_in_cache";
 drop table t1;
+
+#
+# test of SQL_SELECT_LIMIT
+#
+create table t1 (a int);
+insert into t1 values (1),(2);
+show status like "Qcache_queries_in_cache";
+select * from t1;
+SET OPTION SQL_SELECT_LIMIT=1;
+select * from t1;
+show status like "Qcache_queries_in_cache";
+SET OPTION SQL_SELECT_LIMIT=DEFAULT;
+drop table t1;

sql/sql_cache.cc

@@ -743,11 +743,11 @@ void Query_cache::store_query(THD *thd, TABLE_LIST *tables_used)
   if (query_cache_size == 0)
     DBUG_VOID_RETURN;
 
-  if ((local_tables = is_cacheable(thd, thd->query_length,
+  if ((local_tables= is_cacheable(thd, thd->query_length,
 			     thd->query, &thd->lex, tables_used)))
   {
-    NET *net = &thd->net;
-    byte flags = (thd->client_capabilities & CLIENT_LONG_FLAG ? 0x80 : 0);
+    NET *net= &thd->net;
+    byte flags= (thd->client_capabilities & CLIENT_LONG_FLAG ? 0x80 : 0);
     STRUCT_LOCK(&structure_guard_mutex);
 
     if (query_cache_size == 0)
@@ -775,8 +775,10 @@ void Query_cache::store_query(THD *thd, TABLE_LIST *tables_used)
       flags|= (byte) thd->variables.convert_set->number();
       DBUG_ASSERT(thd->variables.convert_set->number() < 128);
     }
-    tot_length=thd->query_length+thd->db_length+2;
-    thd->query[tot_length-1] = (char) flags;
+    tot_length= thd->query_length+thd->db_length+2+sizeof(ha_rows);
+    thd->query[tot_length-1]= (char) flags;
+    memcpy((void *)(thd->query + (tot_length-sizeof(ha_rows)-1)),
+	   (const void *)&thd->variables.select_limit, sizeof(ha_rows));
 
     /* Check if another thread is processing the same query? */
     Query_cache_block *competitor = (Query_cache_block *)
@@ -910,7 +912,7 @@ Query_cache::send_result_to_client(THD *thd, char *sql, uint query_length)
   }
   Query_cache_block *query_block;
 
-  tot_length=query_length+thd->db_length+2;
+  tot_length= query_length+thd->db_length+2+sizeof(ha_rows);
   if (thd->db_length)
   {
     memcpy(sql+query_length+1, thd->db, thd->db_length);
@@ -926,15 +928,18 @@ Query_cache::send_result_to_client(THD *thd, char *sql, uint query_length)
      Most significant bit - CLIENT_LONG_FLAG,
      Other - charset number (0 no charset convertion)
   */
-  flags = (thd->client_capabilities & CLIENT_LONG_FLAG ? 0x80 : 0);
+  flags= (thd->client_capabilities & CLIENT_LONG_FLAG ? 0x80 : 0);
   if (thd->variables.convert_set != 0)
   {
-    flags |= (byte) thd->variables.convert_set->number();
+    flags|= (byte) thd->variables.convert_set->number();
     DBUG_ASSERT(thd->variables.convert_set->number() < 128);
   }
-  sql[tot_length-1] = (char) flags;
-  query_block = (Query_cache_block *)  hash_search(&queries, (byte*) sql,
+  sql[tot_length-1]= (char) flags;
+  memcpy((void *)(sql + (tot_length-sizeof(ha_rows)-1)),
+ 	 (const void *)&thd->variables.select_limit, sizeof(ha_rows));
+  query_block= (Query_cache_block *)  hash_search(&queries, (byte*) sql,
 						   tot_length);
+
   /* Quick abort on unlocked data */
   if (query_block == 0 ||
       query_block->query()->result() == 0 ||

sql/sql_parse.cc

@@ -1029,7 +1029,8 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     /* We must allocate some extra memory for query cache */
     if (!(thd->query= (char*) thd->memdup_w_gap((gptr) (packet),
 						packet_length,
-						thd->db_length+2)))
+						thd->db_length+2+
+						sizeof(ha_rows))))
       break;
     thd->query[packet_length]=0;
     thd->packet.shrink(thd->variables.net_buffer_length);// Reclaim some memory